Bring a large pot of salted water to a rolling boil over high heat. Add the spaghetti and cook for 8 to 10 minutes until al dente. Drain and set aside to cool.

Rinse the cooked spaghetti under cold running water, gently tossing to cool thoroughly. Drain well and transfer to a large mixing bowl.

Wash and chop the vegetables. Halve the cherry tomatoes, dice cucumber and bell peppers, and finely chop the red onion. Slice black olives if using.

Add the cooled spaghetti to the bowl with chopped vegetables. Mix gently to combine.

Drizzle the Italian dressing over the mixture and toss carefully to ensure even coating.

Season with salt and freshly ground black pepper. Optionally, sprinkle with grated Parmesan cheese.

Cover and refrigerate for at least one hour to allow flavors to meld.